Multiple cavity injection molds are known in various embodiments, and desireable in that a single molding apparatus can be used to mold two or more products in a single shot.
Specifically as in the prior art, an inner mold cavity member can be positioned between a pair of opposed mold cores that engage opposed sides of the cavity, to define a pair of separate mold cavities respectively positioned between the inner mold cavity member and the two, opposed mold cores. The mold cores can move in and out to define the pair of opposed mold cavities.
In the above-described conventional embodiment, the sprue for molten molding compound typically enters the mold cavity member in a direction lateral to the direction of motion of the mold cores as they move in and out between a closed, molding position and an open position which the molded products may be removed from the cavities. This necessitates a sharp-angle turn in the sprue, typically in the form of a T connection, with branch sprue lines leading to the respective, opposed mold cavities.
Such a sharp, right-angle turn in the sprue line has been found to be a disadvantage in that it increases the flow resistance of molding compound passing through the sprue, and exhibits other disadvantages as well. Particularly when large volumes of molding compound are required for filling large cavities for molding the lids of drums or the like, the angled design of the sprue, which is also of undesirable length, has been found to exhibit the disadvantages of requiring a very large molding press, and slowing down the speed of operation.
In accordance with this invention, an improvement in such a multiple cavity injection mold is provided, along with an improved mold gate. By this invention, it is possible to achieve molded products of improved dimensional tolerance, coupled with the molding of multiple products in multiple mold cavities, if desired. The multiple mold cavities may be sequentially or simultaneously molded in a single shot, while making use of the improved design of mold sprue and gate of this invention.